Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA.
Lab Chip. 2012 Mar 21;12(6):1052-9. doi: 10.1039/c2lc20887c. Epub 2011 Dec 22.
This article describes a portable microfluidic technology for determining the minimum inhibitory concentration (MIC) of antibiotics against bacteria. The microfluidic platform consists of a set of chambers molded in poly(dimethylsiloxane) (PDMS) that are preloaded with antibiotic, dried, and reversibly sealed to a second layer of PDMS containing channels that connect the chambers. The assembled device is degassed via vacuum prior to its use, and the absorption of gas by PDMS provides the mechanism for actuating and metering the flow of fluid in the microfluidic channels and chambers. During the operation of the device, degas driven flow introduces a suspension of bacterial cells, dissolves the antibiotic, and isolates cells in individual chambers without cross contamination. The growth of bacteria in the chambers in the presence of a pH indicator produces a colorimetric change that can be detected visually using ambient light. Using this device we measured the MIC of vancomycin, tetracycline, and kanamycin against Enterococcus faecalis 1131, Proteus mirabilis HI4320, Klebsiella pneumoniae, and Escherichia coli MG1655 and report values that are comparable to standard liquid broth dilution measurements. The device provides a simple method for MIC determination of individual antibiotics against human pathogens that will have applications for clinical and point-of-care medicine. Importantly, this device is designed around simplicity: it requires a single pipetting step to introduce the sample, no additional components or external equipment for its operation, and provides a straightforward visual measurement of cell growth. As the device introduces a novel approach for filling and isolating dead-end microfluidic chambers that does not require valves and actuators, this technology should find applications in other portable assays and devices.
本文介绍了一种用于测定抗生素对细菌最低抑菌浓度（MIC）的便携式微流控技术。该微流控平台由一组在聚二甲基硅氧烷（PDMS）中模制的腔室组成，这些腔室预先加载有抗生素，干燥后可与第二层 PDMS 可逆密封，该层 PDMS 包含连接腔室的通道。在使用前，组装好的装置通过真空脱气，PDMS 对气体的吸收为微流控通道和腔室中流体的驱动和计量提供了机制。在装置运行过程中，脱气驱动的流动引入细菌细胞悬浮液，溶解抗生素，并将细胞隔离在单独的腔室中，避免交叉污染。在存在 pH 指示剂的情况下，腔室中细菌的生长会产生比色变化，可使用环境光进行目视检测。使用该装置，我们测量了万古霉素、四环素和卡那霉素对粪肠球菌 1131、奇异变形杆菌 HI4320、肺炎克雷伯菌和大肠杆菌 MG1655 的 MIC，并报告了与标准液体肉汤稀释测量值相当的值。该装置为针对人类病原体的单个抗生素 MIC 测定提供了一种简单方法，将在临床和即时医疗领域得到应用。重要的是，该装置的设计简单：它只需进行一次移液操作即可引入样品，操作无需额外的组件或外部设备，并且可以直接目视测量细胞生长。由于该装置采用了一种新颖的方法来填充和隔离无死端微流控腔室，无需阀门和执行器，因此该技术应在其他便携式分析和设备中得到应用。
